Switch operating mechanism



June 24, 1941. w. w. BROWN SWITCH OPERATING MECHANISM Filed 001;. 5i,i940 Invent?Br-: Walter* W own,

His Attorne g.

Patented June 24, 1941 SWITCH OPERATING MECHANHSM Walter W. Brown, Erie,Pa., assignor to General ElectricCompany, a corporation of New YorkApplication October 31, 1940, Serial No. 363,763

(Cl. lat-568) 12 Claims.

My invention relates to switch operating mechanism and is particularlyapplicable to switch operating mechanism provided with a plurality ofcams, such as used in conjunction with electric motor controllers. ofthe drum .ty-pe.

Where a plurality of cams are mounted along the length of a single shaftit is common practies to mount the cams upon a portion of the shafthaving a rectangular cross-section. While this is a simple and effectivedevice for fixing the cams against rotation, it presents considerableinconvenience whenever it is desired to change the angular setting ofany one or more of the cams. For example, it is desired to convert aselected switch from normally closed to normally open, it is necessaryto change the angular position of its cooperating cam with respect tothe shaft. In order to angularly adjust a switchopcrating cam ofconventional design it is first necessary to remove from the shaft thatcam and all other cams lying between it and the end of the. assembly.This inconvenience is particularly undesirable in certain applicationswhere it is necessary frequently to change the normal position of only acertain selected few of a plurality of cam operated switches. In suchapplications, while it is advantageous for reasons of constructionalsimplicity and durability to retain the square-shaft type of mountingfor the cams, it is very desirable to have means provided for angularlyadjusting the selected cams without the necessity of longitudinallydisplacing them any substantial distance.

Accordingly, it is an object of my invention to provide mounting meansfor a switch operating cam permitting angular adjustment of the cam onits shaft.

It is a further object of my invention to provide means for mounting aswitch operating cam upon a shaft of non-circular cross-section whilepermitting angular adjustment of the cam with respect to the shaftwithout substantial longitudinal displacement.

It is characteristic of my invention that one or more cams constructedin accordance therewith may be mounted on a common shaft with one ormore non-adjustable cams and may be adjusted without removing any camfrom the shaft.

To the attainment of the foregoing and other objects and advantages myinvention is preferably embodied in the detailed construction to behereinafter more fully described and claimed, and is illustrated in theaccompanying drawing in which Fig. 1 is an exploded perspective view ofthe component parts of my cam assembly; Fig.

2 is a cross-sectional view taken through the center line of the camshaft and showing the details of the cam and bushing assembly; and Fig.3 is a perspective View of a cam shaft provided with one cam constructedin accordance with my invention and a plurality of conventionalnonadjustable cams.

According to my invention an externally threaded bushing carrying aninternally threaded cam is mounted upon'a shaft of non-circularcross-section and means are provided for securing the cam to the bushingin a plurality of angularly spaced positions.

Referring now to the drawing, the numeral Iii represents, a shaft of thetype upon which my improved cam is adapted to be mounted. As shown inFigs. 1 and 3, the shaft it consists of one or more end portions ofcircular cross-section and a cam-supporting portion I! of noncircularcross-section, shown by Way of example as rectangular. As hereinbeforementioned, cams such as l2 and it of Fig. 3 may be provided with centralapertures of the same configuration as the cross-section of the portionll of the shaft and may be mounted directly upon this portion of theshaft.

Referring now particularly to Fig. 1, my invention comprises a bushingit provided with a rectangular or other non-circular central aperture E5of the same configuration as the cross-section of the shaft portion Hupon which it is to be mounted. The bushing id is preferably ofelectrical insulating material as indicated on the drawing. The externalcylindrical surface of the bushing i4 is threaded, as at It, and isadapted for cooperation with internal threads ll of a circularlyapertured cam it. The cam i8 is likewise preferably composed ofelectrical insulating material.

For the purpose of securing the cam Hi to the bushing i l in any one ofa plurality of angularly spaced positions the bushing M is provided witha plurality of recesses 59. From Figs. 1 and 2 it may be seen that eachof the recesses 59 is provided with a base portion fill forming a seatfor a locking spring 25. Each locking spring 25 includes a diagonallyextending portion 26. As best shown in Fig. 2, the springs 25 are notplanar figures, but the central diagonally extending portions 28 arebowed upward so that when placed in the recesses 19 the portions 26 ofthe springs are raised above the base portions 20 of the recesses. Itwill be understood, of course, that I do not wish to be limited to theparticular number of recesses l9 and springs 25 which I have shown anddescribed, but that any desired number of recesses I9 and springs 25 maybe located in angularly spaced positions about the bushing I l. Forcooperation with any selected locking spring 25 a set screw 27, threadedinto a radial aperture 28 of the cam I8, is provided. An end portion 29of the set screw is provided with one or more diametrical slots 38 ofsufiicient width to embrace the portion 26 of any spring 25.

In looking my improved cam to a shaft procomes into contact with thebowed-up portion 26 of the spring 25. Continued rotation of the setscrew 2'! will begin to depress the portion 26 of the spring 25. Afterthe portion 26 of the spring has been slightly depressed it will springupward into locking engagement with the first diametric'al slot 3|]which is brought into alignment therewith. The set screw 21 may thus bescrewed down until it is sufiiciently tightly locked by the spring 25.

In order to provide for the slight longitudinal displacement of the camI8 as it is rotated upon the bushing I4, the bushing I4 is preferablylarger in longitudinal dimension than the cam I8, and the recesses I9have .a longitudinal dimension somewhat greater than th diameter of theset screw 21.

When the cam I8 is fixed in any one of its possible positions,longitudinal displacement of the cam is prevented by engagement of thethreads I6 of the bushing I4 with the threads I! of the cam I8, whileangular displacement of the cam is pervented by engagement of the sides3| of the spring with the sides of the recess 9- If the spring 25 shouldnot fit snugly into the recess I9, engagement of the end portion 38 ofthe set screw 21 with the sides of the aperture will prevent anysubstantial angular displacement of the cam.

Fig. 3 shows a switch operating mechanism constructed in accordance withmy invention and mounted on a shaft I0 which also carries a plurality ofcams l2 and I3. All the cams I8, I2 and I3 are mounted upon anon-circular section II of the'shaft II], but the cams I2 and I3 arefixedly mounted directly upon the ortion II while the cam I8 isadjustably mounted by means of the bushing I 4. It will, of course, beunderstood that Fig. 3 represents only a portion of a cam shaft assemblyin which any desirednumber of my improved operating mechanisms areassembled in any desired positions among a plurality of conventionalfixedly mounted cams such as l2 and I3.

Fig. 3 also shows a plurality of operating members or switch arms 32, 33and 34 adapted to be positioned by the cams I2, I3 and I8 when the shaftII] is rotated. Since all the arms are similar, only the arm 32 has beenshown in full. As illustrated, the .arm 32 is pivotally mounted upon apin 35 and carries a movable contact 36 cooperating with a relativelyfixed contact 37.

The operating arms 32 63 and 34 are preferably of electrical condflctingmaterial and, being electrically in contact with the contacts 36 and 31,possess a voltage differing appreciably from ground potential. Since thecam shaft III is usually grounded, it will be observed that a potentialgradient will exist along the surface of the cam I8 and the bushing I4.The length of insulating surface along this path is considerably greaterin my operating mechanism than in the conventional cam assembly shown atI2 and I3 in Fig. 3. The length of the insulating surface in myoperating mechanism is increased by two factors; first the end portionsof the bushing I 4 which protrude beyond the side surfaces of the camI8, and second, the threads IE on the bushing I4. By these means, then,the effect of electrical surface creepage, ordinarily disturbing incontrollers of this type, is appreciably diminished.

While I have described a particular preferred embodiment of my inventionby way of example, I wish to have it understood that I do not wish to belimited thereto, and I therefore contemplate y the appended claims tocover all such modifications as fall within the true spirit and scope ofmy invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:

1. In a switch operating mechanism, a plurality of operating members, acam shaft, a cam non-rotatably mounted upon said shaft engaging one ofsaid members, a bushing mounted on said shaft in fixed angular relationthereto, said bushing having a threaded cylindrical external surface, aninternally threaded operating cam mounted on said bushing and engagingone of said members, and means for locking said operating cam to saidbushing in any one of a pillrality of spaced angular positions.

2. In a switch operating mechanism, a plurality of pivotally mountedoperating members, a cam shaft, a plurality of cams non-rotatablymounted upon said shaft, each of said cams engaging one of said members,a bushing mounted upon said shaft in fixed angular relation thereto,said bushing having a threaded cylindrical external surface providedwith a plurality of angularly spacad recesses, an internally threadedoperating cam mounted upon said bushing and having a threaded aperturefor the reception of a set screw, said operating cam engaging one ofsaid members, and a set screw in said aperture for locking saidoperating cam to said bushing in any one of a plurality of predeterminedspaced angular positions.

3. In a switch operating mechanism, a plurality of pivotally mountedswitch operating members, a cam shaft, a plurality of cams non-rotatablymounted upon said shaft, each of said cams engaging one of said members,a bushing mounted upon said shaft in fixed angular relation thereto,said bushing having a threaded cylindrical external surface providedwith a plurality of angularly spaced recesses, an internally threadedoperating cam mounted upon said bushing and having a threaded aperturefor the reception of a set screw, said operating cam being smaller inlongitudinal dimension than said bushing and engaging one of saidmembers, a set screw in. said aperture, and a locking spring positionedin each of said recesses for locking engagement with said set screw. 7 V

4. In a switch operating mechanism, a plurality of pivotally mountedswitch operating arms, a cam shaft of non-circular cross-section, aplurality of cams non-rotatably mounted upon said shaft, each of saidcams engaging one of said arms, a bushing of insulating material mountedon said shaft in fixed angular relation thereto, said bushing having athreaded cylindrical external surface provided with a plurality ofangularly spaced recesses, a locking spring positioned in each of saidrecesses, an operating cam of insulating material mounted in threadedengagement with said bushing, said operating cam having a smallerlongitudinal dimension than said bushing, and a set screw in said camprovided with a grooved end face and positioned for looking engagementwith any one of said locking springs.

5. A cam assembly comprising a cam shaft, a bushing mounted on saidshaft in fixed angular relation thereto, said bushing having a threadedcylindrical external surface, an internally threaded cam mounted uponsaid bushing, a set screw connected to said cam, and a plurality ofseparate resilient locking means associated with said bushing andarranged selectively to engage said set screw to secure said cam to saidbushing in any one of a plurality of predetermined spaced angularpositions.

6. A cam assembly comprising a cam shaft, a bushing mounted on saidshaft in fixed angular relation thereto, said bushing having a threadedcylindrical external surface provided with a plurality of angularlyspaced recesses, an internally threaded cam mounted upon said bushingand having a threaded aperture for the reception of a set screw, and aset screw in said aperture for locking said cam to said bushing in anyone of a plurality of predetermined spaced angular positions.

7. A cam assembly comprising a cam shaft, a bushing mounted on saidshaft in fixed angular relation thereto, said bushing having a'threadedcylindrical external surface provided with a plurality of angularlyspaced recesses, an internally threaded cam mounted upon said bushingand having a threaded aperture for the reception of a set screw, a setscrew in said aperture, and a locking spring positioned in each of saidrecesses for locking engagement with said set screw.

8. A cam assembly comprising .a cam shaft of non-circular cross-section,a bushing mounted on said shaft in fixed angular relation thereto, saidbushing having a plurality of angularly spaced recesses in its externalsurface, a cam rotatably mounted on said bushing, and a set screw insaid cam, a plurality of separate resilient locking means operativelyassociated with said recesses selectively to lock said cam to saidbushing in any one of a plurality of predetermined spaced angularpositions.

9. A cam assembly comprising a cam shaft of non-circular cross-section,a bushing mounted on said shaft in fixed angular relation thereto, saidbushing having a plurality of angularly spaced recesses in its externalsurface, a cam rotatably mounted on said bushing, a set screw in saidcam, and resilient locking means associated with said set screw and saidrecesses for fixing said cam to said bushing in a plurality ofpredetermined spaced angular positions.

10. A cam assembly comprising a cam shaft of non-circular cross-section,a bushing mounted on said shaft in fixed relation thereto, said bushinghaving a plurality of angularly spaced recesses in its external surface,a locking spring positioned in each recess, a cam rotatably mounted onsaid bushing, and a set screw in said cam positioned for lockingengagement with any one of said springs.

11. A cam assembly comp-rising a cam shaft of non-circularcross-section, a bushing mounted on said shaft in fixed angular relationthereto, said bushing having a threaded cylindrical external surfaceprovided with a plurality of angularly spaced recesses, a locking springpositioned in each recess, a cam mounted in threaded engagement withsaid bushing, and a set screw in said cam positioned for lockingengagement with any one of said locking springs.

12. A cam assembly comprising a cam shaft of non-circular cross-section,a loushing mounted on said shaft in fixed angular relation thereto, saidbushing having a threaded cylindrical external surface provided with aplurality of angularly spaced recesses, a locking spring positioned ineach recess, a cam mounted in threaded engagement with said bushing, anda set screw in said a cam provided with .a grooved end face and posi-

